Hey guys. I'm in a new ethical hacking class for my college and coming up with Exercises for the class and decided to post them on here whenever I come up with new ones. Some of the wording would be awkward because I'm just copying it over from my papers so I might refer to you as a student or "us" or "we". I also try to explain to the best of my knowledge what is going on. (I'm sure other people could add to what I already have) If I ever post anything that's wrong let me know so I can edit it.

Assuming you have a clean install of BT4 with no edits:

Ettercap:

Ettercap is a tool for network protocol analysis and security auditing. It has the ability to intercept traffic on a network, capture passwords, and conduct active eavesdropping against common protocols.

For this exercise I will be using ARP Poisoning to sniff the LAN for passwords that use SSL (Hotmail, Gmail, Etc.)

ARP:

“Address Resolution Protocol”: As defined by Wikipedia: ARP is a computer networking protocol for determining a network host's link layer or hardware address when only its Internet Layer (IP) or Network Layer address is known. This function is critical in local area networking as well as for routing internetworking traffic across gateways (routers) based on IP addresses when the next-hop router must be determined.

So in normal terms ARP is the way that we get a MAC address of a Host or Node from the IP address.

ARP Spoofing:

This is the technique we will use to attack a wired or a wireless network. ARP Spoofing allows the attacker to sniff data frames from the LAN, then gives you the ability to modify the traffic (good for redirecting to your own computer to download an exploit to victim), or stop the traffic from entering the network, or a specific computer (good for local DOS Attacks on a Local Area Network).

The idea behind the attack is to send a fake (AKA “Spoofed”) ARP message to the LAN. Any traffic on the network meant for that IP address that you attacked (whole network if you want) will be sent to the attacker. The attacker (you) can choose to forward the traffic to the actual gateway (Passive Sniffing) or modify the data before forwarding it (Man in the Middle).

How we will do it for this exercise:

Edit a file:

We first have to edit one file (Don’t worry, we just have to delete two # signs to “uncomment” them).

The file we will be editing is called etter.conf and it can be found under the etc folder. (Full Path = /etc/etter.conf)

We need to change the part under the “redir_command_on/off” section. It is under the Linux sub heading.

MAKE SURE YOU ONLY UNCOMMENT THE TWO LINES UNDER “if you use iptables” NOTICE: IPTABLES, Not Chains.

Notice how there are no Pound (#) signs in front of the last two lines.

Run Ettercap:

Now we can start Ettercap-GTK (This is a pretty version of the shell program, it gives us a nice GUI to play with). Ettercap-GTK can be found under: Menu -> Backtrack -> Privilege Escalation -> Spoofing -> Ettercap-GTK

Now, you have all the computers on the network on the host list. If you want to only scan one computer (its better and quicker for us to just do the one) then click on the default gateway first, and click the target 1 button.

After you do the default gateway, then click your computer you are attacking and make it “Target 2” by selecting it and clicking the “target 2” button.

After setting up the sniffing:

Mitm -> ARP poisoning -> Select “Sniff remote connections” Hit OK

Start -> Start Sniffing

Your done! Now you are sniffing the computer for passwords onto certain websites that use SSL for their security. When you are done go to: Start -> Stop Sniffing, and then go to Mitm -> Stop mitm attack(s)

Problems:

When you run this, the SSL certificates on some websites will not be valid, so the user has to constantly hit yes for the attack to run successfully. For most users this won’t be a problem seeing as how they “Trust” the site usually and will hit yes.

Protect yourself:

Don’t hit yes for all of the SSL certificates when you know the website should be up to date because you know your being attacked.

I would make one suggestion for you. Don't use wikepedia if you can help it. That is not one of the best sources for accurate information.

02-10-2010, 06:07 PM

boost

Re: Ettercap With ARP Poisoning

Good post, thanks for the share. As for the suggestion about Wikipedia, I thought most classes didn't allow you to put that as a source ;-)

02-10-2010, 06:32 PM

micole

Re: Ettercap With ARP Poisoning

Thanks Archangel. I'll try to stay away from wikipedia. (I only wrote this in a timespan of 2 hours, and I wanted to just give a brief idea of what ARP was and such for people who didn't know.

Moh, I'm going to keep posting information as long as people want me to :)

If anyone has anything they want me to try and write about just let me know and I'll add it to my Ethical Hacking paper. Who knows, eventually I might upload the whole document on here when its done. (for free of course, I might sell it to a book publisher, but I know that the internet is where my bread is buttered :p)

02-13-2010, 05:38 PM

darkman.develop

Re: Ettercap With ARP Poisoning

Great work. Very good explanation.
I will be waiting your next thread.

02-14-2010, 12:30 AM

alexomul

Re: Ettercap With ARP Poisoning

Nice tutorial, well done !

02-14-2010, 01:57 PM

R3104d

Re: Ettercap With ARP Poisoning

Great job man! I wish my school would take from yall as an example and let us focus more on security. Keep up the good work up there.

02-19-2010, 12:40 AM

chkov

Re: Ettercap With ARP Poisoning

Decent post.

But this really is an example of learning people to use programs when they (I think) don't know the slightest about computers||tcp/ip. But I guess to get them curious about computers it's nice to use these kind of topics.

A couple of suggested next lessons:
1. proxies are quite easy to use && explain to people if you yourself understand them. (tor, socat, tsocks, proxychains)
2. To delve further in arpspoofing and the possible uses try dnsspoof to setup a fake login page for your college and then "Let the password collecting begin." NOTE: to get your students accustomed with some command-line tools (of which there are much more than GUIs) use arpspoof. Arpspoof and dnsspoof are both command-line tools and are in the dnsiff package.
3. Maybe aircrack-ng wep cracking, but that's more advanced then 1 && 2 in my opinion.

-chkov

02-19-2010, 08:04 AM

Sniper

Re: Ettercap With ARP Poisoning

Nice work will described.

But I was wondering, why dont you put it here as an attachement or upload it to a server as a word/pdf document so people can download it for future reference.